Unify the three places that patch font loading for PDFium on Windows.

content/renderer/render_thread_impl_browsertest.cc

Index: content/renderer/render_thread_impl_browsertest.cc
diff --git a/content/renderer/render_thread_impl_browsertest.cc b/content/renderer/render_thread_impl_browsertest.cc
index 3e4a795a9ed38a01ac1e9d9cf937ced534b98c08..bda8944a8314766538b70a9a7ba6587bb2b49087 100644
--- a/content/renderer/render_thread_impl_browsertest.cc
+++ b/content/renderer/render_thread_impl_browsertest.cc
@@ -77,6 +77,12 @@ class TestTaskCounter : public base::SingleThreadTaskRunner {
   int count_;
 };
 
+#if defined(COMPILER_MSVC)
+// See explanation for other RenderViewHostImpl which is the same issue.
+#pragma warning(push)
+#pragma warning(disable: 4250)
+#endif
+
 class RenderThreadImplForTest : public RenderThreadImpl {
  public:
   RenderThreadImplForTest(const std::string& channel_id,
@@ -91,12 +97,16 @@ class RenderThreadImplForTest : public RenderThreadImpl {
     RenderThreadImpl::SetResourceDispatchTaskQueue(test_task_counter_);
   }
 
-  using ChildThread::OnMessageReceived;
+  using ChildThreadImpl::OnMessageReceived;
 
  private:
   scoped_refptr<TestTaskCounter> test_task_counter_;
 };
 
+#if defined(COMPILER_MSVC)
+#pragma warning(pop)
+#endif
+
 void QuitTask(base::MessageLoop* message_loop) {
   message_loop->QuitWhenIdle();
 }